Common industrial heat exchangers include multiple tubes placed between two tubesheets and encapsulated in a pressure vessel shell. Fluids or gasses of differing temperatures are passed through the heat exchanger, transferring the heat energy from one medium to the other. The tubes may be press fit or welded in place. Where the separation of the liquids or gasses is critical, as in nuclear heat exchangers and chemical plants, the tubes must be welded in place and checked for leaks prior to entering service. The process of welding the heat exchanger tubes has many drawbacks including: (1) high labor costs to prepare and weld all of the tube joints via manual fusion welding techniques, (2) defect repair costs due to the complex manual or semi-automatic fusion welding process, and (3) increased corrosion susceptibility of the fusion welding joint. Corrosion is a major cause of working fluid contamination, especially where one of the systems is corrosive.